In the related art, games are known in which the image of a part of a user's body such as a head is captured by a video camera, in which a predetermined area for an eye, a mouth, a hand, or the like is then extracted, and in which the area is replaced with another image for display on a display (for example, patent document No. 1). A user interface is also known that receives, as an instruction for operating an application, the movement of a mouth or a hand captured by a video camera.
[Patent document No. 1] European Patent Application No. 0999518